DateUtil.getDaysBetween(Date, Date, TimeZone) does not recognize Daylight Saving Time.

• Type: Bug
• Status: Closed
• Resolution: No Longer Reproducible
• Affects Version/s: 6.1.0 CE GA1, 6.1.1 CE GA2
• Fix Version/s: 6.2.0 CE M4
• Component/s: Legacy Components, Legacy Components > API
• Labels:
  • community-verifier
• Environment: Tested on LR 6.1.0 CE GA1/Java6/Tomcat/WinXP (according to the javadoc, GA2 did not change this method).

DateUtil.getDaysBetween(Date, Date, TimeZone) has a one-off-error around midnight during the TimeZone's Daylight Savings timespan.

Reproduction is problematic (it's only noticeable in the FriendsActivities Portlet during daylight savings time either when checking between 23:00 and 23:59 or when looking later at an activity from that timespan – the "today" and "yesterday" headers are in the wrong position).

For testing, I added this code in view.jsp of the FriendsActivities portlet:

<%!
         public int getDaysCountBetween(Date date1, Date date2, TimeZone timeZone) {
         // copy of com.liferay.portal.kernel.util.DateUtil.getDaysBetween()
         // one line was changed (marked by a comment below)
                 if (date1.after(date2)) {
                         Date tempDate = date1;
                         date1 = date2;
                         date2 = tempDate;
                 }
                 Calendar startCal = null;
                 Calendar endCal = null;
                 int offset = 0; 
                 if (timeZone == null) {
                         startCal = new GregorianCalendar();
                         endCal = new GregorianCalendar();
                 }
                 else {
                         startCal = new GregorianCalendar(timeZone);
                         endCal = new GregorianCalendar(timeZone);
                         offset = timeZone.getOffset(date2.getTime()); // this line is changed compared to trunk
                 }
                 startCal.setTime(date1);
                 startCal.add(Calendar.MILLISECOND, offset);
                 endCal.setTime(date2);
                 endCal.add(Calendar.MILLISECOND, offset);
                 int daysBetween = 0; 
                 while (CalendarUtil.beforeByDay(startCal.getTime(), endCal.getTime())) {
                         startCal.add(Calendar.DAY_OF_MONTH, 1);
 
                         daysBetween++;
                 }
                 return daysBetween;
         }
         %>
<%
Format df = FastDateFormatFactoryUtil.getSimpleDateFormat("dd.MM.yyyy HH:mm z", locale, TimeZone.getTimeZone("Europe/Berlin"));
Date date0 = new SimpleDateFormat().parse("07.07.2012 20:30"); //parsing UTC time!
Date date1 = new SimpleDateFormat().parse("07.07.2012 21:30");
Date date2 = new SimpleDateFormat().parse("07.07.2012 22:30");
Date date3 = new SimpleDateFormat().parse("07.07.2012 23:30");
Date date4 = new SimpleDateFormat().parse("07.07.2012 24:30");
%>
Date0: <%= df.format(date0) %><br/>
Date1: <%= df.format(date1) %><br/>
Date2: <%= df.format(date2) %><br/>
Date3: <%= df.format(date3) %><br/>
Date4: <%= df.format(date4) %><br/>
getDaysCountBetween(0, 1): <%= getDaysCountBetween(date0, date1, TimeZone.getTimeZone("Europe/Berlin")) %><br/>
DateUtil.getDaysBetween(0, 1): <%= DateUtil.getDaysBetween(date0, date1, TimeZone.getTimeZone("Europe/Berlin")) %><br/>
getDaysCountBetween(1, 2): <%= getDaysCountBetween(date1, date2, TimeZone.getTimeZone("Europe/Berlin")) %><br/>
DateUtil.getDaysBetween(1, 2): <%= DateUtil.getDaysBetween(date1, date2, TimeZone.getTimeZone("Europe/Berlin")) %><br/>
getDaysCountBetween(2, 3): <%= getDaysCountBetween(date2, date3, TimeZone.getTimeZone("Europe/Berlin")) %><br/>
DateUtil.getDaysBetween(2, 3): <%= DateUtil.getDaysBetween(date2, date3, TimeZone.getTimeZone("Europe/Berlin")) %><br/>
getDaysCountBetween(3, 4): <%= getDaysCountBetween(date3, date4, TimeZone.getTimeZone("Europe/Berlin")) %><br/>
DateUtil.getDaysBetween(3, 4): <%= DateUtil.getDaysBetween(date3, date4, TimeZone.getTimeZone("Europe/Berlin")) %><br/>

The output of this is as follows (getDaysCountBetween is my patched function, DateUtil.getDaysBetween the trunk method; comments added manually):

Date0: 07.07.2012 22:30 MESZ
Date1: 07.07.2012 23:30 MESZ
Date2: 08.07.2012 00:30 MESZ
Date3: 08.07.2012 01:30 MESZ
Date4: 08.07.2012 02:30 MESZ
getDaysCountBetween(0, 1): 0      //correct
DateUtil.getDaysBetween(0, 1): 0  //correct
getDaysCountBetween(1, 2): 1      //correct
DateUtil.getDaysBetween(1, 2): 0  //incorrect
getDaysCountBetween(2, 3): 0      //correct
DateUtil.getDaysBetween(2, 3): 1  //incorrect
getDaysCountBetween(3, 4): 0      //correct
DateUtil.getDaysBetween(3, 4): 0  //correct

As you see, DateUtil.getDaysBetween() returns the "one day difference" in the wrong case while my corrected version above returns the correct differences. All I did was replacing the line

                            offset = timeZone.getRawOffset();

with

                            offset = timeZone.getOffset(date2);

in com.liferay.portal.kernel.util.DateUtil line 153 (method getDaysBetween).

getRawOffset() is the wrong method to use; I cite from it's javadoc: "Because this value is not affected by daylight saving time, it is called raw offset." (see http://docs.oracle.com/javase/6/docs/api/java/util/TimeZone.html#getRawOffset%28%29)